route_processing.c

Siproxd is a proxy/masquerading daemon for the SIP protocol. It handles registrations of SIP client

/* -*- Mode: C; c-basic-offset: 3 -*-
    Copyright (C) 2002-2005  Thomas Ries <[e-mail]>

    This file is part of Siproxd.
    
    Siproxd is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
    
    Siproxd is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with Siproxd; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
*/

#include "config.h"

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <osipparser2/osip_parser.h>
#include <osipparser2/sdp_message.h>

#include "siproxd.h"
#include "log.h"

static char const ident[]="$Id: route_processing.c,v 1.7 2005/03/01 21:36:48 hb9xar Exp $";

/* configuration storage */
extern struct siproxd_config configuration;	/* defined in siproxd.c */


/*
 * PROXY_PREPROCESS_ROUTE
 *
 * Route Information Preprocessing
 * 
 * RETURNS
 *	STS_SUCCESS on success
 */
int route_preprocess(sip_ticket_t *ticket){
   osip_message_t *mymsg=ticket->sipmsg;
   int sts;
   osip_uri_t *url;
   int dest_port;
   int last;
   struct in_addr addr1, addr2, addr3;
   osip_route_t *route;
   osip_uri_param_t *param=NULL;

   if ((mymsg->routes==NULL) || (osip_list_size(mymsg->routes)<=0)) {
      DEBUGC(DBCLASS_PROXY, "route_preprocess: no Route header present");
      return STS_SUCCESS;
   }

   if (get_interface_ip(IF_INBOUND, &addr2) != STS_SUCCESS) {
      return STS_FAILURE;
   }
   if (get_interface_ip(IF_OUTBOUND, &addr3)!= STS_SUCCESS) {
      return STS_FAILURE;
   }

   /*
    * 16.4 Route Information Preprocessing:
    * The proxy MUST inspect the Request-URI of the request.  If the
    * Request-URI of the request contains a value this proxy previously
    * placed into a Record-Route header field (see Section 16.6 item 4),
    * the proxy MUST replace the Request-URI in the request with the last
    * value from the Route header field, and remove that value from the
    * Route header field.  The proxy MUST then proceed as if it received
    * this modified request.
    */
   url = osip_message_get_uri(mymsg);
   dest_port= (url->port)?atoi(url->port):SIP_PORT;

   if (get_ip_by_host(url->host, &addr1) == STS_SUCCESS) {
      if ((configuration.sip_listen_port == dest_port) &&
          (url->username && (strcmp(url->username,"siproxd")==0)) &&
          ((memcmp(&addr1, &addr2, sizeof(addr1)) == 0) ||
           (memcmp(&addr1, &addr3, sizeof(addr1)) == 0))) {
         /* Request URI points does to myself */
         DEBUGC(DBCLASS_PROXY, "request URI [%s@%s:%i] points to myself",
                (url->username)?url->username:"*NULL*",
                (url->host)?url->host:"*NULL*",
                (url->port)?atoi(url->port):SIP_PORT);
         /* get last route in list */
         last=osip_list_size(mymsg->routes)-1;
         route = (osip_route_t *) osip_list_get(mymsg->routes, last);
         DEBUGC(DBCLASS_PROXY, "moving last Route [%s@%s:%i] to URI",
                (route->url->username)?route->url->username:"*NULL*",
                (route->url->host)?route->url->host:"*NULL*",
                (route->url->port)?atoi(route->url->port):SIP_PORT);

         /* issue warning if the Route I'm going to fetch is NOT
            a strict router (lr parameter not present) - something is fishy */
         if (osip_uri_uparam_get_byname(route->url, "lr", &param) == 0) {
            WARN("Fixup Strict Router: Route entry [%s@%s:%i] is not "
                 "a strict Router!",
                (route->url->username)?route->url->username:"*NULL*",
                (route->url->host)?route->url->host:"*NULL*",
                (route->url->port)?atoi(route->url->port):SIP_PORT);
         }

         /* rewrite request URI */
         osip_uri_free(url);
         osip_uri_clone(route->url, &(mymsg->req_uri));

         /* remove from list */
         osip_list_remove(mymsg->routes, last);
         osip_route_free(route);
      }
   } else {
      WARN("cannot resolve host in Request URI [%s]", url->host);
   }


   /*
    * 16.4 Route Information Preprocessing:
    * If the first value in the Route header field indicates this proxy,
    * the proxy MUST remove that value from the request.
    */
   DEBUGC(DBCLASS_PROXY, "route_preprocess: checking topmost "
          "Route header");
   route = (osip_route_t *) osip_list_get(mymsg->routes, 0);
   if ((route != NULL) && (route->url != NULL) &&
       (route->url->host != NULL)) {
      sts = get_ip_by_host(route->url->host, &addr1);

      /* my own route header? */
      if ((sts == STS_SUCCESS) &&
          ((memcmp(&addr1, &addr2, sizeof(addr1)) == 0) ||
           (memcmp(&addr1, &addr3, sizeof(addr1)) == 0)) &&
           (route->url->port ?
               configuration.sip_listen_port == atoi(route->url->port):
               configuration.sip_listen_port == SIP_PORT)) {
         osip_list_remove(mymsg->routes, 0);
         osip_route_free(route);
         /* request->routes will be freed by osip_message_free() */
         DEBUGC(DBCLASS_PROXY, "removed Route header pointing to myself");
      }
   }

   return STS_SUCCESS;
}


/*
 * PROXY_POSTPROCESS_ROUTE
 *
 * Route Information Postprocessing
 * 
 * RETURNS
 *	STS_SUCCESS on success
 */
int route_postprocess(sip_ticket_t *ticket){
   osip_message_t *mymsg=ticket->sipmsg;
   osip_uri_t *url;
   osip_route_t *route=NULL;
   osip_uri_param_t *param=NULL;

   /*
    * RFC 3261, Section 16.6 step 6
    * Proxy Behavior - Request Forwarding - Postprocess routing information
    *
    * If the copy contains a Route header field, the proxy MUST
    * inspect the URI in its first value.  If that URI does not
    * contain an lr parameter, the proxy MUST modify the copy as
    * follows:
    *
    * -  The proxy MUST place the Request-URI into the Route header
    *    field as the last value.
    *
    * -  The proxy MUST then place the first Route header field value
    *    into the Request-URI and remove that value from the Route
    *    header field.
    */

   if (mymsg->routes && !osip_list_eol(mymsg->routes, 0)) {

      route = (osip_route_t *) osip_list_get(mymsg->routes, 0);
      if (route->url) {
         /* check for non existing lr parameter */
         if (osip_uri_uparam_get_byname(route->url, "lr", &param) != 0) {
            osip_route_t *new_route=NULL;
            url=osip_message_get_uri(mymsg);

            /* push Request URI into Route header list at the last position */
            osip_route_init(&new_route);
            osip_uri_clone(url, &new_route->url);
            osip_list_add(mymsg->routes, new_route, -1);

            /* rewrite request URI to now topmost Route header */
            DEBUGC(DBCLASS_PROXY, "Route header w/o 'lr': rewriting request "
                   "URI from %s to %s", url->host, route->url->host);
            osip_uri_free(url);
            url=NULL;
            osip_uri_clone(route->url, &url);
            /* remove first Route header from list & free */
            osip_list_remove(mymsg->routes, 0);
            osip_route_free(route);
            route = NULL;
         }
      }
   }
   return STS_SUCCESS;
}


/*
 * PROXY_ADD_RECORDROUTE
 *
 * Add a Record-route header
 * 
 * RETURNS
 *	STS_SUCCESS on success
 */
int route_add_recordroute(sip_ticket_t *ticket){
   osip_message_t *mymsg=ticket->sipmsg;
   int sts;
   int position;
   struct in_addr addr;
   osip_record_route_t *r_route;
   osip_uri_t *uri_of_proxy;

   /*
    * RFC 3261, Section 16.6 step 4
    * Proxy Behavior - Request Forwarding - Add a Record-route header
    */

   /*
    * get the IP address of the interface where I'm going to
    * send out this request
    */
   switch (ticket->direction) {
   case REQTYP_INCOMING:
   case RESTYP_INCOMING:
      if (get_interface_ip(IF_INBOUND, &addr) != STS_SUCCESS) {
         return STS_FAILURE;
      }
      break;
   case REQTYP_OUTGOING:
   case RESTYP_OUTGOING:
      if (get_interface_ip(IF_OUTBOUND, &addr) != STS_SUCCESS) {
         return STS_FAILURE;
      }
      break;
   default:
      ERROR("Oops, never should end up here (direction=%i)", ticket->direction);
      return STS_FAILURE;
   }

   sts = osip_record_route_init(&r_route);
   if (sts == 0) {
      sts = osip_uri_init(&uri_of_proxy);
      if (sts == 0) {
         char tmp[8];

         /* host name / IP */
         osip_uri_set_host(uri_of_proxy, osip_strdup(utils_inet_ntoa(addr)));
         osip_uri_set_username(uri_of_proxy, osip_strdup("siproxd"));

         /* port number */
         sprintf(tmp, "%i", configuration.sip_listen_port);
         osip_uri_set_port(uri_of_proxy, osip_strdup(tmp));

         /* 'lr' parameter */
         osip_uri_uparam_add(uri_of_proxy, osip_strdup("lr"),NULL);

         osip_record_route_set_url(r_route, uri_of_proxy);

         position=0;
         /* if it is a response, add in to the end of the list
          * (reverse order as in request!) */
         if ((ticket->direction==RESTYP_INCOMING) ||
             (ticket->direction==RESTYP_OUTGOING)) {
            position = -1;
         }

         /* insert into record-route list*/
         osip_list_add (mymsg->record_routes, r_route, position);

      } else {
          osip_record_route_free(r_route);
      } /* if url_init */
   } /* if record route init */


   return STS_SUCCESS;
}


/*
 * PROXY_PURGE_RECORDROUTE
 *
 * Purge Record-Route headers pointing to myself.
 * 
 * RETURNS
 *	STS_SUCCESS on success
 */
int route_purge_recordroute(sip_ticket_t *ticket){
   osip_message_t *mymsg=ticket->sipmsg;
   osip_record_route_t *r_route=NULL;
   int last, i, sts;
   struct in_addr addr1, addr2, addr3;

   if (mymsg->record_routes) {
      last=osip_list_size(mymsg->record_routes)-1;
      /* I *MUST NOT* purge any alien (non-mine) Record-Route headers,
       * only the ones I've put in myself! */
      if (last >= 0) {
         for (i=last; i>=0; i--) {
            r_route = (osip_record_route_t *)
                      osip_list_get(mymsg->record_routes, i);

            /* skip empty entries */
            if (r_route == NULL) continue;
            if (r_route->url == NULL) continue;
            if (r_route->url->host == NULL) continue;

            /* resolve IP addresses (of RR header, inbound & outbound IF) */
            sts = get_ip_by_host(r_route->url->host, &addr1);
            if (get_interface_ip(IF_INBOUND, &addr2) != STS_SUCCESS) {
               return STS_FAILURE;
            }
            if (get_interface_ip(IF_OUTBOUND, &addr3) != STS_SUCCESS) {
               return STS_FAILURE;
            }

            /* check if my own route header? */
            if ((sts == STS_SUCCESS) &&
                ((memcmp(&addr1, &addr2, sizeof(addr1)) == 0) ||
                 (memcmp(&addr1, &addr3, sizeof(addr1)) == 0)) &&
                 (r_route->url->port ?
                     configuration.sip_listen_port == atoi(r_route->url->port):
                     configuration.sip_listen_port == SIP_PORT)) {

               osip_list_remove(mymsg->record_routes, i);
               osip_record_route_free(r_route);
               DEBUGC(DBCLASS_PROXY, "removed Record-Route header pointing "
                      "to myself");
            }
         } // for
      } // if
   }
   return STS_SUCCESS;
}


/*
 * PROXY_DETERMINE_NEXT_HOP
 *
 * check if a route-header exists and give back the next hop
 * 
 * RETURNS
 *	STS_SUCCESS on success
 */
int route_determine_nexthop(sip_ticket_t *ticket,
                            struct in_addr *dest, int *port){
   int sts;
   osip_message_t *mymsg=ticket->sipmsg;
   osip_route_t *route=NULL;

   /*
   * Check for existing route header. If so, the topmost will be
   * the next hop.
   *
   * If this route header does NOT have a lr parameter set, rewrite
   * the SIP URI to point to the destination of the route (NOT IMPLEMENTED)
   */
   if (mymsg->routes && !osip_list_eol(mymsg->routes, 0)) {

      /* get the destination from the Route Header */
      route = (osip_route_t *) osip_list_get(mymsg->routes, 0);
      if (route==NULL || route->url==NULL || route->url->host==NULL) {
         DEBUGC(DBCLASS_PROXY, "route_determine_nexthop: got broken Route "
                "header - discarding packet");
         return STS_FAILURE;
      }

      sts = get_ip_by_host(route->url->host, dest);
      if (sts == STS_FAILURE) {
         DEBUGC(DBCLASS_PROXY, "route_determine_nexthop: cannot resolve "
                "Route URI [%s]", route->url->host);
         return STS_FAILURE;
      }

      if (route->url->port) {
         *port=atoi(route->url->port);
      } else {
         *port=SIP_PORT;
      }

      osip_list_remove(mymsg->routes, 0);
      osip_route_free(route);
      /* request->routes will be freed by osip_message_free() */
   }

   return STS_SUCCESS;
}